The present invention relates to a wheel drum structure of an inner stator portion with inbuilt switches and, more particularly, to a wheel drum type electromotor or generator having an inner stator portion with inbuilt switches and a plurality of sets of stator coils.
FIG. 1 shows an exploded perspective view of a prior art outer rotor wheel drum type electromotor or generator, whose outer rotor portion 61 comprises a magnet iron yoke ring 611, an outer rotor housing 612, a housing cover plate 613, a bearing 614, and an outer rotor magnet 615. The outer rotor portion 61 has an inner stator 71, wire heads/tails 419 of coils, an axial through hole 312, and an axial through inner hole 315 therein.
In a conventional stator device, a stator portion thereof has a plurality of stator coils, which are switched according to the rotation speed of a rotor to generate the torsion coefficient KT of various kinds of levels. If the KT is changed timely, an electromotor can obtain the optimal power performance of xe2x80x9clow rotation speed and high torsionxe2x80x9d and xe2x80x9chigh rotation speed and high horsepowerxe2x80x9d. Simultaneously, the plurality of sets of stator coils are switched according to the rotation speed of the outer rotor to generate the counter electromotive force coefficient KE of various kinds of levels. If the KE is changed timely, an electromotor or generator can maintain the operational characteristic of high efficiency for all operational regions.
However, wire heads/tails of the plurality of stator coils will increase the count of output wire heads/tails of the electromotor or generator several-fold. Therefore, the wiring operation will be complex and inconvenient. The present invention aims to resolve this problem.
A stator portion of a conventional electromotor or generator is formed by winding a single stator coil. Therefore, the torsion coefficient KT and the counter electromotive force coefficient KE thereof are consequentially constant values. This can be illustrated with the following formulas.
wherein E is the counter electromotive force voltage (volt), T is the output torsion (Nxe2x88x92m), KE is the counter electromotive force coefficient, KT is the torsion coefficient, xcexa9 is the rotation speed of the armature (rad/sec), Ia is the armature current (ampere), B is the magnetic flux density of the air gap (gauss), D is the outer diameter of the armature (cm), L is the superimposed thickness (cm), and Z is the total number of turns of conductors.
As can be seen from the above formulas, the counter electromotive force coefficient KE equals the torsion coefficient KT, and the values of KE and KT are proportional to the total number of turns of conductors Z. Therefore, if the total number of turns of conductors Z of a coil in an identical electromotor or generator changes, the values of the counter electromotive force coefficient KE and the torsion coefficient KT vary accordingly.
If an electromotor or generator is to be operated at a high rotation speed with a certain counter electromotive force voltage E, the counter electromotive force coefficient KE is inevitably lower. Therefore, the output torsion T is necessarily lower. If a larger torsion T is required, it is necessary to increase the armature current Ia. However, a too large Ia is not good to the operational efficiency of the electromotor. This can be known from the following formula.
P=I2xc2x7R
wherein P is the dissipated power of the coil of the stator portion, I is the armature current, and R is the impedance of the coil. Therefore, if the torsion of an electromotor is increased by increasing the armature current, the dissipated power of the coil of the stator portion will increase squarely, and heat will be generated in the impedance of the coil. The impedance of the coil will correspondingly rise due to the temperature rise of the metallic coil. This vicious circle will let the electromotor or generate operate in an environment of high temperature, hence resulting in a worse output efficiency.
A stator portion of a conventional electromotor or generator is formed by winding a single stator coil. Therefore, the torsion coefficient KT and the counter electromotive force coefficient KE thereof are consequentially constant values. The operational region thereof having better efficiency is much limited. In the present invention, the area of wire grooves of an inner stator portion is deepened and enlarged, and a plurality of sets of coil windings of various turns are disposed therein. A hollow inner hole is formed at an inner ring portion end of the inner stator. Two end cover plates at the inner ring portion end cover two end faces of the hollow inner hole. The inner ring portion end forms a hollow space after being covered to dispose switches therein. Complex wiring operations of the plurality of sets of the stator coils and the switches are thus completed in the structure. By means of systematized management and control, the turns of the inner stator coils can have diversified variations. Variations of the turns of the coils can change the values of the counter electromotive force coefficient KE and the torsion coefficient KT of the electromotor or generator. If the values of the KE and KT are varied timely, the highest rotation speed of the electromotor will change accordingly, or the highest output voltage of the generator will change accordingly. Therefore, as shown in FIGS. 9A and 9B, because a stator portion has a plurality of values of KE and KT, the operational region of optimal efficiency generated by each of the values of KE and KT can be included in the range of low, middle, or high rotation speed. In other words, the characteristic of high efficiency EFF value can be maintained within a wide range of operational rotation speed. Moreover, if the electromotor needs to work within the range of low rotation speed, a highest value of the torsion coefficient KT can be obtained once a stator coil of the highest turns is switched to. Contrarily, if the electromotor needs to work within the range of high rotation speed, a lowest value of the counter electromotive force coefficient KE can be obtained once a stator coil of the least turns is switched to. Therefore, by switching the stator coils of different turns, an electromotor can obtain the optimal power output characteristic of xe2x80x9clow rotation speed and high torsionxe2x80x9d and xe2x80x9chigh rotation speed and high horsepowerxe2x80x9d.
An electromotor or generator of the present invention can acquire the operational characteristic of uniform and high efficiency within a wide operational range and the optimal power characteristic of xe2x80x9clow rotation speed and high torsionxe2x80x9d and xe2x80x9chigh rotation speed and high horsepowerxe2x80x9d. Moreover, excess space at the ring portion end of the inner stator can be fully exploited. Furthermore, complexity and inconvenience of wiring operations occurring in the prior art can be resolved under the premise that the original volume of a wheel drum type electromotor or generator is not enlarged, hence resolving complexity and inconvenience of wiring engineering.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing, in which: